This invention relates generally to torque control shutoff clutches for power tools and the like and more particularly to a controlled fluid shutoff and reset mechanism for a fluid operated tool.
Fluid operated tools for driving fasteners and the like typically incorporate a rotary vane air motor to drive a rotary shaft connected to a tool bit. Such tools are often equipped with a clutch mechanism that responds to the torque imparted by the tool to the fastener. When a specific torque is reached, the clutch mechanism automatically decouples the motor from the tool bit and terminates further tool output to the fastener.
It is desirable that the decoupling and shutoff occur as cleanly and as closely as possible to a desired applied torque. If the motor is not decoupled there occurs substantial inertial followup which may overtighten the fastener and lead to greater torque reaction on the operator. If the motor is not shut off upon clutch release it will continue to run without accomplishing useful work until the operator shuts it off.
In addition, an automatic reset of the mechanism is a desirable feature. A particular problem of prior art devices has been the inability to achieve clean clutch jaw disengagement and lockout near the point of shutoff thereby producing damage to the clutch face components and a ratcheting impact effect as the device coasts to a stop.
The foregoing illustrates limitations known to exist in torque control shutoff devices for power tools. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully described hereinafter.